This application is based on and claims priority to Japanese Patent Application No. 11-304,648 filed Oct. 26, 1999, the entire contents of which are hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to fuel injection control systems for engines, and more particularly to fuel injection control systems that are suitable for outboard motors.
2. Related Art
Outboard motors are used to power boats and other watercraft. Outboard motors typically include an internal combustion engine that is surrounded by a protective cowling. In order to improve performance, and in particular fuel efficiency and emissions, many outboard motors use a fuel injection system to supply fuel to the engine. Fuel injection systems often include fuel injectors that inject fuel directly into an air induction device. The amount of fuel injected through the fuel injectors is determined by a control system, which usually includes an electronic control unit (ECU). Typically, the ECU determines the desired amount of fuel and the corresponding fuel/air ratio based upon the engine speed and load. The fuel injection system, therefore, can improve performance by precisely controlling the fuel/air ratio for each cycle of the engine over a wide variety of engine running conditions.
In general, the engine of an outboard motor is started by turning the crankshaft manually or with a started motor. When the engine is being started, engine speed cannot be determined until the engine completes one or more revolutions. Accordingly, during starting, fuel injection systems typically do not deliver fuel to the fuel injectors immediately. This prevents the engine from operating immediately upon starting and requires the crankshaft to be turned longer. However, because outboard motors often are operated under harsh conditions, it is desirable that they start quickly. Moreover, during starting, a battery often provides the power to turn the crankshaft. Thus, having to turn the crankshaft longer tends to drain the battery.
Accordingly, there is a need for a for an improved fuel injection control system that enables the engine to start more quickly.
One aspect of the present invention involves an internal combustion engine that includes at least one combustion chamber formed by at least a first member and a second member that moves relative to the first member. The second member is coupled to an output shaft such that movement of the second member causes the output shaft to rotate. A fuel injection system includes a fuel injector that supplies fuel to the combustion chamber and a fuel pump that supplies fuel to the fuel injector. The fuel injector includes an actuator to regulate an amount of fuel injected by the fuel injector. A main switch has an on position and an off position. A fuel control system includes a controller. which is operatively connected to the actuator, and a sensor, which is arranged to detect rotation of the output shaft. The sensor is adapted to produce a signal that is indicative of rotation of the output shaft and is operatively connected to the controller. The controller is configured such that, when the engine is operating and the main switch is turned from the on position to the off position, the controller outputs a control signal to the actuator so that fuel is no longer injected through the fuel injector. After a specified time, the controller outputs a control signal to the actuator to inject a second amount of fuel when the sensor indicates that the output shaft is rotating below a specified speed.
Another aspect of the present invention involves a method of stopping an internal combustion engine. The engine includes a combustion chamber, a crankshaft, a main switch, a fuel pump, and a fuel injector. The main switch is turned off and the fuel injection through the fuel injector is stopped. A rotational speed of the crankshaft is sensed. If the rotational speed of the crankshaft is below a specified value, an amount of fuel is injected through the fuel injector after the specified time.
Yet another aspect of the present invention involves an internal combustion engine comprising at least one combustion chamber that is formed by at least a first member and a second member that moves relative to the first member. The second member is coupled to an output shaft such that movement of the second member causes the output shaft to rotate. A fuel injection system includes a fuel injector that supplies fuel to the combustion chamber and a fuel pump that supplies fuel to the fuel injector. The engine further including means for providing fuel to the combustion chamber before the crankshaft begins rotation.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.